JPS60149768A - Metallized film having high adhesion - Google Patents

Abstract

PURPOSE:To obtain stable electric discharge even during low voltage and to form a film having high adhesion with high efficiency by shaping an acceleration voltage in the pulse form and performing metallization with the pulse peak value thereof as an abnormal glow discharge area or glow arc transfer area. CONSTITUTION:A peak value and a base value are set in a pulse oscillating circuit 10 and the voltage is modulated to the higher frequency in order to rectify the AC voltage increased by a transformer 6 to DC by a rectifier stack 7 and shaping the DC voltage in the pulse form. The set values are compared and amplified with the value detected in a current detector 9 in a differential amplifier 11 and a power control transistor 8 is controlled by the differential signal thereof to regulate the pulse width of the high frequency so as to attain the set pulse voltage. The pulse voltage is thus made to the value approximate to the max. value of the abnormal glow discharge or glow arc area in the above- mentioned way, by which the efficiency of metallization is improved. Since the voltage is made into lower pulses by modulating the high-frequency pulses, the pulse discharge is easily accomplished even during the low pulses and the quality of the metallized film is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a sputter metallization method using pulsed energy, and particularly to a highly efficient metallization method that provides a film with high adhesion.

[Background of the invention]

The sputter metallization method utilizes the phenomenon in which accelerated ions collide with a target and the energy causes atoms and molecules on the target surface to be ejected to the outside.

FIG. 1 shows the principle of the general DC bipolar sputtering method. DC high voltage power supply 1. It is composed of an anode 2, a substrate 3, a negative electrode 4, and a chamber 5. Generally, the atmosphere of the chamber 5 is an Ar gas atmosphere, and the pressure is 10-' to 10-
Sputtered at 3 Torr. When the atmospheric pressure is kept constant and the voltage is increased, the evaporation from the target 4 increases.If it increases further, the glow discharge shifts to an arc discharge, and the current is concentrated in places where the current easily flows, such as protrusions. This will damage the target and the board, making it unusable. Furthermore, since the temperature of the substrate increases as the voltage increases, sputter deposition is generally performed at around 3 KV in DC bipolar sputtering and around 0.6 KV in magnetron sputtering. Therefore, there are drawbacks such as the inability to obtain a film with high efficiency and good adhesion. Further, as a modification of the above method, there is a method in which a film is formed by intermittently discharging. this is.

The purpose is to reduce the temperature rise of the substrate and metallize the plastic by discharging intermittently. It is known that in order to improve film quality, it is better to perform discharge in a low thickness. However, because it discharges intermittently, the discharge at low pressure becomes unstable. Additionally, there are drawbacks such as poor efficiency due to intermittent discharge.

[Purpose of the invention]

The object of the present invention is to provide an entire pulse metallization method that solves the problems described as I''i, provides a highly efficient and highly adhesive film, and provides stable discharge even at low pressures.

[Summary of the invention]

The present invention has focused on the fact that the discharge phenomenon at low pressure shows the light, pressure, and flow curves shown in FIG. Sputter metallization is generally performed in the emmetropic claw discharge and abnormal claw discharge regions. The present invention pulses the accelerating voltage [7, this pulse 7 [pressure is set near the highest value of abnormal glow discharge or in the glow arc region to improve efficiency, and modulates the high frequency pulse to reduce the pulse d)・All features include high quality so that pulse discharge can be easily performed even at low pressure. FIG. 3 shows pulse emission 1 of the present invention. A schematic diagram of the waveform is shown. [2
As shown in 1, the high frequency pulse is modulated to reduce the pulse.

The voltage V4i is the peak voltage of the high frequency pulse, and v3 is the average value of the high frequency pulse voltage at time r1, which is taken as the peak voltage at the low frequency. Also, ■ 1 digit time T
The pulse width of the high frequency pulse at 2 is made small, the average false pressure is lowered, and the base voltage is set at 2 at low frequency. v2 is the average soil that depends on the low frequency, and the peak voltage and base voltage at the frequency are set by changing the high frequency pulse width, so low pulse discharge in a low pressure atmosphere is effective.

[Embodiments of the invention]

Examples will be described below with reference to FIGS. 4 to 7.

Figures 2 and 4 are schematic diagrams of the present invention. The AC voltage and voltage boosted by the transformer 1 are connected, and converted to DC by the 7-hole stack 7.
In order to pulse the DC voltage, it is set to a peak pulse value and a base value in the pulse detection circuit 10, and is further modulated to a high frequency. The set value is compared and amplified with the value detected by the current detector 9 in the differential amplifier 11, and the power control transistor 8 is controlled by the 1-point difference signal to adjust the high frequency pulse width so that the set pulse becomes a voltage. I'm making adjustments. In addition, in the abnormal glow discharge region, voltage and current are in a proportional relationship, so the current was controlled. This is because if constant voltage control is used, if for some reason the circuit enters the arc discharge region, a large current will flow and destroy the transistor. In addition, the sputtering method was a magnetron method. A magnet 12 is attached to the back surface of the target 4 so that Ar ions can efficiently hit the target. The thermocouple 13 measures the entire temperature of the curtain plate.

The sputtering conditions are: target: copper (150x50x1t
), board-to-sword, distance from target to board: 3
5mm, atmospheric pressure 28 x 10-3 Torr (
A, r), Pace TAR: 0. LA constant, peak discharge 1 hour (T 1) 10 base discharge time (T2)
=10mSeC constant, high frequency pulse frequency: 500
KHz.

Average current: 0.5A constant, pulse peak current (voltage) completely changed (because the average current is constant 0.5A, changing the peak value will also change the pulse width) 1. Film thickness and vehicle flow (voltage) is shown in FIG. average'
When the current is kept constant at 0.5A and the peak current is increased,
Along with this, the film thickness has increased, and at 12A, it is 1.7 times that of the DC method (the DC method is the DC magnetron method) Q and 5A. In the 12A discharge region, the current increases in the glow arc transition region, and the voltage is 500V lower than the voltage of 1800V at the maximum m flow of 6A in the abnormal glow arc region. However, the arc was not concentrated and discharged over the entire target area, and the target was not destroyed. However, at 30A, the concentration of arc decreased by h3. That is, it is desirable that the pulse peak I - is the maximum value of the abnormal glow family π or the beginning of the low arc transition stage) υ]. On the other hand, the substrate temperature after 30 minutes of discharge is 96'C for the DC method, and 100'C for the pulse peak "R flow of 6A, 12A for the present invention".
It is 103'C, which is not much different from the DC method. However, in the present invention, the film thickness is 1.7 times greater. In addition, in order to make the film thickness the same as the film thickness of 1.3 μm 1 min in the DC method, a case was investigated in which the Vi6A, 30 minute discharge was changed to 15 minutes in the present invention, and the film thickness was made almost the same as the DC method. As a result, the temperature was 45° C., and with the same jIQ thickness, it was possible to reduce the substrate temperature to 1/2.

In addition, the adhesion strength was examined under the above conditions. The test method involved gluing cylindrical rods together with epoxy adhesive and then pulling the rods down to examine the adhesion strength. As a result, the present invention has 55
The g/w'-DC method has a value of 36 g/mm2, which is an increase of 40 g/mm2 compared to the conventional method.

In addition, it is thought that even though the average current (voltage) is the same as that of the DC method, the peak energy is large, so the adhesion strength is increased. From the above results, it is clear that it is effective to set the pulse peak value to the highest value of the abnormal glow discharge or the first 1υ1 step of the glow arc. Set it to a constant value of 6,
Also, the base current, [1: (], I A (constant)
, T1+T2=10 m5ec (constant), the pulse width ratio of the peak current was varied, and the relationship between the film thickness and the current (voltage) was compared with that of the DC method. The results are shown in FIG. When the variable average current is in the range of 0.5 to 3A, it is 1.4 to 1 compared to the DC method.
．． Eight times the film thickness can be obtained. However, above 3A, the difference decreases as the average current increases and becomes the same value at about 5A.

That is, the pulse width T1 of the peak current is '1'l+'I
It is desirable that it be 80% or less of '2.

These trends were also observed in metals such as At and AH.

Further, FIG. 7 shows an example of a 3,c+Bt-Nr gold alloy used as an insert material for diffusion bonding and the like. In the DC method, the current is 3A, and in the present invention, when the current is 3.5A, it is 3.9Br-N.
+ The gold alloy target cracked due to thermal strain and further experiments could not be conducted. However, in the present invention, a film thickness of 1.6 to 2 times that of the DC method can be obtained in the range of 0.5 to 3. Thus, it is clear that the present invention is effective for particularly fragile targets.

In addition, similar experiments were conducted using the conventional pulse discharge method, but pulsed lightning under an atmospheric pressure of 9 x 10-2 Torr or less was unstable and formed a good film, but it was not possible to evaluate the adhesion strength etc. Ta. However, in the present invention, 3×10-”l'o
Stable pulse eccentricity was obtained up to rr, and a film with high density and good adhesion was formed. In addition, the present invention can metalize nonconducting targets at high speed and with high quality by using not only DC pulses but also high-frequency AC pulses4). Furthermore, by changing the target portion to a wafer, it is possible to use it for dry etching and perform high speed dry etching.

〔Effect of the invention〕

As is clear from the above examples, the pulse discharge voltage can be set to the highest voltage of abnormal claw discharge or glow-arc transition [
By doing so, even if the average voltage is low, the ion energy during pulse discharge is very small, so the adhesion is good, and the adhesion strength is increased by a factor of 40 compared to the conventional DC method (DC magnetron method). In addition, even in low-pulse discharge, the high-frequency pulse is modulated to reduce the pulse, making it easier to discharge at low pressure.
A dense film with little gas adsorption can be obtained. On the other hand, due to the reasons mentioned above, the film thickness rate is 1.5% compared to the conventional method.
~2 times the film thickness rate can be obtained. If the film thickness is the same as in the DC method, the temperature of the substrate can be set to 172°C, so damage to the substrate and target can be prevented.

[Brief explanation of the drawing]

Figure 1 is a diagram of the principle of the conventional DC bipolar sputtering method, Figure 2 is a diagram showing the discharge phenomenon in a low pressure atmosphere, Figure 3 is a comparison diagram of the discharge waveforms of the present invention and the conventional method, and Figure 4 is A diagram of the principle of the present invention. Figure 5 is an example of the effect of the present invention, and is an explanatory diagram of the relationship between peak height and film thickness. Figures 6 and 7 are examples of the effect of the present invention, and the peak value is determined by abnormal glow discharge. It is a diagram showing the relationship between the peak value and the film thickness when the pulse width of the peak value is changed. 2...Anode, 3...Substrate, 4...Target, 6
...Step-up transformer, 9...Current detector, 10...
Pulse oscillator, Figure 1 Section 4 80 Lesby-2 Zero piezoelectric: t/

Claims (1)

[Claims] 1. A highly adhesive metallized film characterized by being metalized with a pulse peak value as an abnormal glow discharge region or a glow-arc transition region.